1. Field of the Invention
The present invention relates to a plastic rivet consisting of a rivet body comprised of a flanged head and a leg member extending from the bottom of the head, and a pin which when inserted into an axial through-hole of the rivet expands the leg member.
2. Description of the Prior Art
Because of their convenience as fasteners for components requiring periodic inspection and maintenance, rivets of the type which can be fastened and unfastened by insertion and extraction of a pin into and from a rivet body are coming into increasingly wide use. The conventional rivet of this type has, however, not been entirely satisfactory. One problem has been that since the structure employed makes it difficult to obtain adequate expansion of the leg member by insertion of the pin it has been necessary to make the diameter of the axial through-hole close to the outer diameter of the leg member. As a result, a high degree of processing precision is required in forming the rivet body and, worse, the rivet is often unable to provide the tight fastening force that is desired.
Another problem with the conventional fastener has been that when a rivet in the fastened condition is to be unfastened by pushing the pin further into the rivet body, the pin is apt to come all the way out the other end of the rivet body and fall in among the other components of the device in which it is used. In this case, if the pin cannot be found it of course cannot be reused, but an even greater problem is that it may interfere with the operation of the device.
One of the reasons for these shortcomings of the conventional rivet is that since the leg member which is expanded by the insertion of the pin is formed to have a plurality of legs either by providing one or more cuts axially inward from the tip of the leg member or by a plurality of axial slits provided in the intermediate section of the leg member so that when the pin is inserted, all of the legs spread outward by the same amount.